In conventional cylinder type vacuum cleaners, a motor arranged in a housing of the vacuum cleaner drives a fan, which causes air to be displaced radially outwards of the fan and expelled through vents in the housing. This in turn causes suction upstream of the fan, which draws dirty air into the vacuum cleaner housing, through a suitable filter such as a rigid filter element or a flexible filter bag, the filter being located between an inlet or the housing and the fan. As a result, dirty air is drawn along a suitable accessory such as a flexible hose connected to the housing inlet, enters the inlet and passes through the filter, and cleaner air passes through the fan and is expelled through the vents in the housing.
Known vacuum cleaners of this type suffer from the drawback that if the filter should be removed, for example for emptying or cleaning, while the motor is operating the fan, dirty air can be drawn directly towards the fan without being filtered, as a result of which dirt can cause damage to the motor.